Circuit breakers such as gas-blast circuit breakers are known, for example, in high-voltage technology.
By way of example, WO 98/43265 discloses a gas-blast circuit breaker. The circuit breaker includes a first arc contact which can be driven, a second, stationary arc contact, a rated-current path which runs concentrically with respect to them, and a compression device in order to compress quenching gas in a blowout volume. The compressed quenching gas is used to quench an arc, which is created when the first arc contact is disconnected from the second arc contact, by blowing it out with quenching gas.
The first arc contact, which can be driven, is supported by a switching tube. An exhaust volume is provided at an outlet from this switching tube, into which the quenching gas is passed after blowing out the arc. The exhaust volume, which is arranged within the rated-current path, is connected to a low-pressure area outside the rated-current path, via blowout openings. Furthermore, the exhaust volume is separated by a separating wall from an induction area, which is arranged between the blowout volume and the exhaust volume, likewise within the rated-current path. This induction area is connected to the blowout volume via a purging valve and via an overpressure valve. The moving switching tube is passed through the separating wall, in a sealed manner.
With this known gas-blast circuit breaker, the gas pressure in the induction area can be maintained approximately constant such that the gas pressure in the exhaust volume does not influence the operation of the purging valve or the operation of the overpressure valve. However, the separating wall is arranged within the tubular rated-current path. Since the separating wall is subject to a high pressure difference between the induction area and the exhaust volume while the first arc contact is being disconnected from the second arc contact, the separating wall should be attached robustly to an inner wall of the rated-current path, and a sealed bushing is provided for the switching is tube through this separating wall.
A high-voltage circuit breaker is also known from US 2003/0173335 A1 (and DE 603 05 552 T2, which corresponds to this U.S. document). This known circuit breaker has an evacuation line between a thermal chamber and an expansion area, which evacuation line is arranged axially symmetrically with respect to the movement axis of the moving contacts. The evacuation line, which runs in the axial direction, is closed by a valve, which opens when the overpressure in the thermal arc quenching chamber is high.
EP 0 146 671 A1 discloses a further gas-blast circuit breaker. To keep a pressure in a piston volume from rising above a predetermined value during opening of the gas-blast circuit breaker, this gas-blast circuit breaker has a radially arranged overpressure valve in an effort to have gas flow away through this overpressure valve when the overpressure in the piston volume is excessive.
EP 0 296 363 A2 discloses a gas-blast circuit breaker with a quenching gas flow that is produced by the circuit breaker itself. This gas-blast circuit breaker has a compression area. To address an excessive pressure in the compression area, this gas-blast circuit breaker has a valve through which gas can flow out radially from the compression area.